Cation Doping and Suppression of Charge Order in Sr_1-xLa_xCoO₃

Charge ordering (CO) is a prominent feature of strongly correlated electron systems, however the exact origin of such phenomena and the consequences for physical properties are still being explored. Many doped Mott insulators show both electronic phase separation and CO. One example is SrCoO_3-y. As the oxygen concentration varies, the crystal structure evolves smoothly but magnetism in the compound shows two-phase behavior, separating into regions with differing ferromagnetic phases. The stable phases are associated with the special oxygen concentrations of SrCoO₃, SrCoO_2.88 and SrCoO_2.75 and support ferromagnetic phases with transition temperatures at 280K, 220K and 160K. Soft X-ray scattering revealed distinct charge ordering for SrCoO_2.75 ad SrCoO_2.88. The same overall Co-charge balance can be achieved by mixing La onto Sr-sites rather than introducing oxygen vacancies. Our recent study reveals that the cation doping suppresses both phase separation and charge ordering on these materials. We performed Resonant Elastic X-ray Scattering on La-doped SrCoO₃ thin films, after confirming the epitaxy and the presence of magnetic phases with XRD and SQUID. We deposited thin films of various thickness of Sr_0.75La_0.25CoO₃ on both STO and LAO substrates using Pulsed Laser Deposition.